Universal laboratory prototyping interface system

ABSTRACT

The invention includes a main circuit board which is coupled by a 68 pin SCSI-2 connector to a National Instruments DAQ (PCI-6024E or equivalent) which resides in an expansion slot of a personal computer running National Instruments LABVIEW software which has been modified to include a custom communications driver. The main circuit board includes a communications module, a manual control module, a function generator, an analog I/O module, a current amplifier and frequency calibration module, and an address and status module. The main circuit board is also provided with a first edge connector for receiving a removable protection board which has a second edge connector for receiving a removable prototyping breadboard. The protection board protects the main circuit board and the DAQ from circuit faults on the prototyping breadboard. The main circuit board communicates with the DAQ via 8 digital I/O lines.

This application claims the benefit of Ser. No. 60/225,228 filed Aug.15, 2000, the complete disclosure of which is hereby incorporated byreference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to electronic development systems. Moreparticularly, the invention relates to a prototyping interfacing systemfor use with a personal computer to test and evaluate electroniccircuits.

2. Brief Description of the Prior Art

It is now common to utilize personal computers in the design and testingof electronic circuits. For example, multi-purpose input-output dataacquisition cards (MIO) are available from companies like NationalInstruments Corporation, Austin, Tex. These cards plug into an expansionslot of a personal computer and come bundled with software which enablesthe computer to function as virtual test equipment. For example, theLabVIEW software from National Instruments Corporation emulates avoltmeter and an oscilloscope and can be programmed to perform somesignal processing.

At present, there is no standard way to connect a DAQ to a prototypecircuit for testing and evaluation. Moreover, the presently availableMIO not provide or emulate waveform function generators of fullyfeatured digital multimeters.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide a fully featuredelectronics prototyping system.

It is also an object of the invention to provide a fully featuredelectronics prototyping system which operates in conjunction with apersonal computer.

It is another object of the invention to provide a fully featuredelectronics prototyping system which has a standard interface forconnecting with circuits to be tested and evaluated.

It is yet another object of the invention to provide a fully featuredelectronics prototyping system which includes a waveform functiongenerator and a fully featured digital multimeter.

In accord with these objects which will be discussed in detail below,the invention includes a main circuit board which is coupled by a 68 pinSCSI-2 connector to a National Instruments DAQ card (PCI-6024E orequivalent) which resides in a PCI slot of a personal computer runningNational Instruments LabVIEW software which has been enhanced to includea custom communications driver. The main circuit board includes acommunications module, a manual control module, a function generator, ananalog I/O module, a current amplifier and frequency calibration module,and an address and status module. The main circuit board is alsoprovided with a first edge connector for receiving a removableprotection board which has a second edge connector for receiving aremovable prototyping breadboard. The protection board protects the maincircuit board and the DAQ from circuit faults on the prototypingbreadboard. The main circuit board communicates with the DAQ via 8digital I/O lines.

The communications module supports 8-bit write, 7-bit addressing, 1-bitparity checking, and 8-bit read. The communications module is usedprimarily to set the function generator and the digital multimeter andthus a data transfer rate of approximately 2400 bps is sufficient.

The function generator module utilizes inexpensive digital to analogconverters and analog switching gates to control a low cost analogfunction generator chip. The controls are latched, so the functiongenerator can hold its state indefinitely. It can be controlled from thepersonal computer or from the manual control module as well. Thefunction generator can generate sine, triangle and square waves fromapproximately 0.1 Hz to 250 kHz. The waveform choice, coarse frequency,fine frequency, amplitude, and direct current (DC) voltage offset areall programmable. In addition, it has amplitude modulation (AM) andfrequency modulation (FM) inputs from the prototyping breadboard andinternally via the DAQ analog outputs. The waveform output andsynchronous digital output both feed back into the DAQ via analog gates.This allows for automatic calibration and dynamic auto-tuning offrequency, amplitude and DC offset.

Using analog gates and simple linear circuits, the analog I/O moduleroutes the analog inputs and analog outputs of the DAQ to emulate afull-featured digital multimeter. In addition, it functions as both a2-terminal and 3-terminal I-V curve tracer capable of characterizingdiodes, transistors, etc.

The function generator and analog I/O modules use a fraction of the 128addresses available to the DAQ. According to the presently preferredembodiment, 16 output addresses and 16 input addresses are dedicated foruse by the prototyping board. Using an addressing bus made available onthe prototyping board, the 8-bit data written to the prototyping boardcan be directed to 16 separate addresses. In addition, the prototypingboard read bus can accept data from 16 separate output buffers. Thisallows for the development of sophisticated circuits. In addition, 32more addresses have been reserved for future use by the prototypingboard.

The invention provides a complete turnkey electronics design and testingsolution in a desktop module about the size of a small VCR. It hastremendous flexibility for modification and expansion. The presentinvention has been designed to be a complete, affordable,computer-interfaced electronics design station including a full suite ofsoftware-based test and measure instruments. It has been designed forall experience levels, including educational interests, particularly foruse at the college/university level, high school/technical collegelevel, industrial/commercial setting, as well as personal/hobbyist use.

The invention goes beyond the traditional breadboard “trainer” with thepower and flexibility of computer-based instrumentation.

Because the invention has both commercial and educational applications,the terms “prototyping board”, “prototyping breadboard”, and “studentboard” are used herein interchangeably.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a high level block diagram of the main circuit board, DAQcard, and personal computer;

FIG. 2 is a plan view illustrating the presently preferred layout of thecomponents of the invention;

FIG. 3 is a schematic diagram illustrating details of the communicationsmodule;

FIG. 4 is a schematic diagram illustrating details of the manual controlmodule;

FIG. 5 is a schematic diagram illustrating details of the functiongenerator module;

FIG. 6 is a schematic diagram illustrating details of the functiongenerator and variable DC interface module;

FIG. 7 is a schematic diagram illustrating details of the analog I/Omodule;

FIG. 8 is a schematic diagram illustrating details of the currentamplifier and frequency calibration module;

FIG. 9 is a schematic diagram illustrating details of the circuits usedin the protection board; and

FIGS. 10 and 11 are a schematic diagram illustrating details of theaddress and status module.

BRIEF DESCRIPTION OF THE APPENDIX

The custom communication driver of the invention is included herewith onan ISO 9660 format CDROM. As mentioned above, the communications driveris intended to be used with National Instruments LabVIEW software whichis available in versions for WINDOWS, UNIX, SUN SPARC and MACINTOSHoperating systems. The filename of the driver is “ulis comm core.llb”.It is a LabVIEW library file containing the main program “ulis comm coredriver.vi” and 18 custom subprograms (subvis). It was written in LabVIEW6.0 on a Windows 98 machine and can be opened with LabVIEW 6.0 or higheron any LabVIEW-compatible platform. The documentation is built into thefront panels and diagrams of the various program components.

DETAILED DESCRIPTION

Turning now to FIG. 1, the invention includes a main circuit board 10which is coupled by a 68 pin SCSI-2 connector 12 to a NationalInstruments DAQ (PCI-6024E or equivalent) 14 which resides in a PCI slotof a personal computer running National Instruments LabVIEW software 16which has been modified to include a communications driver 18.

The main circuit board 10 includes a communications module 20, a manualcontrol module 22, a function generator 24 and associated interface 25,an analog I/O module 26, a current amplifier and frequency calibrationmodule 28, and an address and status module 30. These components arecoupled to each other as shown in FIG. 1.

Referring now to FIG. 2, the main circuit board 10 is also provided witha first edge connector 32 for receiving a removable protection board 34which has a second edge connector 36 for receiving a removableprototyping breadboard 38. The edge connectors 32, 36 are preferablyEISA 98 pin edge connectors. A pair of card slides 40, 42 are located oneither side of edge connector 32. The cards 34 and 38 areinstalled/removed by sliding them in the direction of the arrow A. Thus,the prototyping board 38 may be installed with or without the protectionboard 34.

As illustrated schematically in FIG. 2, the presently preferredembodiment includes a front panel 44 which is controlled by the manualcontrol module (22 in FIG. 1), a power cord 46, and a power switch 48.The front panel 44 has a plurality of dials and switches which can beused to operate the circuits on the main circuit board and/or which canbe used by the prototyping board. Details of the manual control moduleare illustrated in FIG. 4.

The protection board 34 protects the main circuit board and the DAQ fromcircuit faults on the prototyping breadboard. It includes a number offuses 50, resistor network chips 52 and diode network chips 54. Detailsof the protection board 34 are illustrated in FIG. 9.

Referring once again to FIG. 1, the main circuit board 10 communicatesvia the communications module 20 with the DAQ 14 via 8 digital I/O lines56. The communications module 20 supports 8-bit write, 7-bit addressing,1-bit parity checking, and 8-bit read. The communications module 20 isused primarily to set the function generator 24 (via the functiongenerator interface 25 ) and the analog I/O module 26 (via the currentamplifier and frequency calibration module 28). Thus, a data transferrate of approximately 2400 bps is sufficient. Details of thecommunications module are illustrated in FIG. 3.

The function generator module 24 (and interface 25) utilizes inexpensivedigital to analog converters and analog switching gates to control a lowcost analog function generator chip. The controls are latched, so thefunction generator can hold its state indefinitely. It can be controlledfrom the personal computer or from the front panel (44 in FIG. 2) aswell. The function generator can generate sine, triangle and squarewaves from 0.1 Hz to 250 kHz. The waveform choice, course frequency,fine frequency, amplitude, and direct current (DC) voltage offset areall programmable via the interface 25. In addition, the frequencygenerator module 24 has amplitude modulation (AM) and frequencymodulation (FM) inputs 58 from the prototyping breadboard and internallyvia the DAQ analog outputs 60. The waveform output and synchronousdigital output 62 both feed back into the DAQ via analog gates in theanalog I/O module 26. This allows for automatic calibration and dynamicauto-tuning of frequency, amplitude and DC offset. Details of thefunction generator module and associated interface are illustrated inFIGS. 5 and 6.

The analog I/O module 26 uses analog gates and simple linear circuits toroute the analog inputs and analog outputs of the DAQ 14 to emulate afull-featured digital multimeter. In addition, it functions as both a2-terminal and 3-terminal I-V curve tracer capable of characterizingdiodes, transistors, etc. Details of the analog I/O module areillustrated in FIG. 7.

The function generator and analog I/O modules 24, 26 use a fraction ofthe 128 addresses available to the DAQ. According to the presentlypreferred embodiment, 16 output addresses and 16 input addresses arededicated for use by the prototyping board. Using an addressing bus madeavailable on the prototyping board, the 8-bit data written to theprototyping board can be directed to 16 separate addresses. In addition,the prototyping board read bus can accept data from 16 separate outputbuffers. This allows for the development of sophisticated circuits. Inaddition, 32 more addresses have been reserved for future use by theprototyping module.

As mentioned above, FIGS. 3-11 illustrate the components of theinvention is detail. Those skilled in the art will have a betterappreciation of these Figures through reference to the following partslist.

Category Subgroup Item Description Internal Electronics Board DigitalLogic 74HC02 quad NOR 74HC04 hex Inverter 74HC08 quad AND 74HC32 quad OR74HC74 dual D latch 74HC85 4 bit comparator 74HC123 dual one shot74HC138 3 to 8 decoder 74HC139 dual 2 to 4 decoder 74HC148 8 to 3encoder 74HC154 4 to 16 decoder 74HC157 quad 2 in mux 74HC165 parallelto serial 8 bit 74HC175 quad D latch 74HC273 octal D latch 74HC280parity generator 74HC541 octal tri-state buffer 74HC595 serial toparallel 8 bit 74HCT541 octal tri-state buffer Digital BidirectionalGating 74HC4053 triple 2-ch analog mux Analog Gating 74HC4051 8-chanalog mux 74HC4053 triple 2-ch analog mux DG509 (Harris) dual 4 to 1analog mux Digital to Analog Converters TLC7226 (Tex. Inst.) quad 8-bitDAC AD7523 (Analog four quadrant 8- Dev.) bit mult DAC FunctionGenerators XR2206 (Exar) sin, sq, tri, function generator OperationalAmplifiers LM741 741 op amp LM348 quad 741 op amp LF411 JFET op ampTransistors 2N3904 npn 100 mA 2N3906 pnp 100 mA High Stabil- ity TimingCapacitors 100 u tantalum 80 u tantalum 10 u tantalum 1 u tantalum 0.1 upolystyrene 10 n polystyrene 2.2 n polystyrene 1 n polystyrene Trim Pots5k 15 turn potentiometer 10k 15 turn potentiometer 20k 15 turnpotentiometer 50k 15 turn potentiometer 100k 15 turn potentiometerSingle-in- Line Bussed Resistors 100k 10 pin Connectors 98 pin EISA cardstandard edge extended ISA 68 pin D-type connect to E- (uwscsi) seriesDAQ 26 pin ribbon connect to front panel Individual Resistors ¼ w metalfilm 5% (appx numbers) ½ w metal film 5% (appx numbers) ¼ w carbon 10%(appx numbers) Capacitors misc value ceramic (appx numbers) 10 uelectrolytic (appx numbers) FrontPanel 2″ × 9″ inch, Board double sided,.02″ linewidth Switches 8 position rotary 8 position rotary w/kbob 3position rotary 3 position rotary w/knob momentary momentary pushbuttonpushbutton spst toggle spst toggle 4pst student DC power switchPotentio- meters 100k single turn w/ knob LEDs standard multiple colorsConnectors 26 pin ribbon connect to internal board Individual Resistors¼ w carbon 10% (appx numbers) Capacitors misc value ceramic ceramic(appx numbers) 10 u electrolytic (appx numbers) Protection Estimate: 10″x 3″ Board double-sided, plated-thru, Fuses .007″ linewidth 10 A slow 10A slow 1.5 A fast 1.5 A fast ⅛ A fast ⅛ A fast Soldered PC Mount FuseHolder Pairs standard fuse standard fuse holders holders (pair)Dual-in-Line Resistor 100 ohm isolated 16 pin DIP 1k isolated 16 pin DIPDual-in-Line Diodes 100 mA Isolated 8 ch bussed DIP IC sockets 16 pinstandard 16 pin DIP Connectors 98 pin EISA card standard edge extendedISA Student 12″ × 10″ inch, Board double sided, .02″ linewidthBreadboards 640 tie point (3M) work area 100 tie point (3M) voltagerails Soldered Tie Points 1 × 5 PC mount (3M) tie points to PC boardtraces 2 × 5 PC mount (3M) tie points to PC board traces 3 × 5 PC mount(3M) tie points to PC board traces 1 × 2 LED PC mnt tie points w/ (3M)LED slot LEDs 5 V LEDs w/internal resistor 12 V LEDs w/internal resistorConnectors Banana (Deltron) PC mount side entry 9-pin D-type PC mountmale, standard serial PowerSupply Transformer 5 tap, center tap for +12V, +5 V @ ˜1.5 A Voltage Regulators w/Heat Sinks 7905 Pos 5 V @ 1.5 A7805 Neg 5 V @ 100 mA 7912 Pos 12 V @ 1.5 A 7812 Neg 12 V @ 1.5 A Diodes1N4001 power diodes Capacitors 1000 u @ 50 V input stabilizer caps 100 uA 35 V output stabilizer caps AC Line power entry module integrated fuseand 120/220 standard power country of cord destination Fan AC is betterDC brushless are noisy

There have been described and illustrated herein methods and apparatusfor prototyping electronic circuits. While particular embodiments of theinvention have been described, it is not intended that the invention belimited thereto, as it is intended that the invention be as broad inscope as the art will allow and that the specification be read likewise.It will therefore be appreciated by those skilled in the art that yetother modifications could be made to the provided invention withoutdeviating from its spirit and scope as so claimed.

1. An electronic circuit prototyping system, comprising: a) a personalcomputer having at least one expansion slot; b) a multi-purpose dataacquisition card installed in said expansion slot; c) softwareassociated with said data acquisition card residing in memory of saidpersonal computer and being in communication with said data acquisitioncard, said software including a custom communication driver; and d) aninterface board coupled to said data acquisition card for connecting toa circuit to be tested, said interface board including i) acommunication module for communicating with said data acquisition cardand said associated software via said custom communication driver, ii) afunction generator interface and variable DC voltage module coupled tosaid communication module, iii) a function generator module coupled tosaid function generator interface and variable DC voltage module, iv) ananalog I/O module coupled to said communication module and to saidfunction generator interface and variable DC voltage module, v) acurrent amplifier and frequency calibration module coupled to saidcommunication module, to said function generator module, and to saidanalog I/O module, and vi) a first edge connector for receiving one of aprototyping board and a protection board, said first edge connectorbeing coupled to said communication module, to said function generatorinterface and variable DC voltage module, to said function generatormodule, to said analog I/O module, and to said current amplifier andfrequency calibration module.
 2. The system according to claim 1,wherein: said communications module supports 8-bit write, 7-bitaddressing, 1-bit parity checking, and 8-bit read.
 3. The systemaccording to claim 2, wherein: said communications module has a datatransfer rate of approximately 2400 bps.
 4. The system according toclaim 3, wherein: said function generator module utilizes inexpensivedigital to analog converters and analog switching gates to control a lowcost analog function generator chip.
 5. The system according to claim 4,wherein: said digital to analog converters and analog switching gatesare latched, so that said function generator can hold its stateindefinitely.
 6. The system according to claim 5, wherein: said functiongenerator can generate sine, triangle and square waveforms fromapproximately 0.1 Hz to 250 kHz.
 7. The system according to claim 6,wherein: waveform choice, coarse frequency, fine frequency, amplitude,and direct current (DC) voltage offset are all programmable.
 8. Thesystem according to claim 7, wherein: said function generator hasamplitude modulation (AM) and frequency modulation (FM) inputs coupledto said first edge connector and to said analog I/O module.
 9. Thesystem according to claim 8, wherein: waveform output is fed back intosaid data acquisition card via analog gates.
 10. The system according toclaim 9, wherein: said analog I/O module includes analog gates andsimple linear circuits for routing analog inputs and analog outputs ofsaid data acquisition card to emulate a full-featured digitalmultimeter.
 11. The system according to claim 10, wherein: said analogI/O module functions as both a 2-terminal and 3-terminal I-V curvetracer capable of characterizing diodes and transistors.
 12. The systemaccording to claim 11, wherein: said interface board further includesvii) a manual control module and front panel coupled to saidcommunication module, to said function generator interface and variableDC module, to said function generator module, to said analog I/O module,and to said current amplifier and frequency calibration module.
 13. Thesystem according to claim 12, wherein: said function generator can becontrolled from said personal computer or from said manual controlmodule and front panel.
 14. The system according to claim 13, wherein:said interface board further includes viii) an address and status modulecoupled to said communication module, to said function generatorinterface and variable DC module, to said analog I/O module, to saidcurrent amplifier and frequency calibration module and to said firstedge connector.
 15. The system according to claim 14, wherein: saidinterface board further includes ix) a protection board installed insaid first edge connector, said protection board having a second edgeconnector for receiving a prototyping board.
 16. The system according toclaim 15, wherein: said protection board includes at least one fuse, atleast one resistor network, and at least one diode network.